Related Experiment Video

Updated: Aug 13, 2026

Instrumentation of Near-term Fetal Sheep for Multivariate Chronic Non-anesthetized Recordings
14:40

Instrumentation of Near-term Fetal Sheep for Multivariate Chronic Non-anesthetized Recordings

Published on: October 25, 2015

Acute blockade of beta 1-receptors in the asphyxiated sheep fetus

A Dagbjartsson, I Kjellmer, K G Rosén

    Acta Physiologica Scandinavica
    |July 1, 1987
    PubMed

    The effects of acute beta 1-blockade on fetal cardiovascular reactions during asphyxia were evaluated in 11 exteriorized sheep fetuses. Gestational age was 110-142 days. Asphyxia was induced either by ventilating the mother with low oxygen gas mixture or by mechanical reduction of placental blood flow. During asphyxia all fetuses reacted to metoprolol injection with a decrease in heart rate, myocardial contractility, cardiac output and arterial blood pressure. Five experiments resulted in irreversible fetal cardiovascular collapse. Isoprenaline was given to the fetuses during hypoxia to test the ability to further increase heart rate and activate myocardial beta-adrenoceptors. In those experiments with fetal cardiovascular demise after metoprolol, the isoprenaline injection did not result in a significant tachycardia. The surviving fetuses could increase their heart rate as a sign of a capacity to further increase the sympatho-adrenergic drive.

    More Related Videos

    The Perinatal Asphyxiated Lamb Model: A Model for Newborn Resuscitation09:03

    The Perinatal Asphyxiated Lamb Model: A Model for Newborn Resuscitation

    Published on: August 15, 2018

    In Vivo Real-Time Study of Drug Effects on Carotid Blood Flow in the Ovine Fetus11:59

    In Vivo Real-Time Study of Drug Effects on Carotid Blood Flow in the Ovine Fetus

    Published on: April 28, 2023

    Related Concept Videos

    Adrenergic Antagonists: ɑ and β-Receptor Blockers01:31

    Adrenergic Antagonists: ɑ and β-Receptor Blockers

    Third-generation β-blockers, such as labetalol and carvedilol, represent a significant advancement in managing cardiovascular conditions. Unlike conventional β-blockers, which can induce peripheral vasoconstriction, third-generation drugs block α1 adrenoceptors. This promotes vasodilation through several mechanisms, such as increased nitric oxide production, inhibition of calcium ion entry, opening of potassium ion channels, and antioxidant action. Labetalol, for instance, is clinically...
    Nondepolarizing (Competitive) Neuromuscular Blockers: Pharmacological Actions01:27

    Nondepolarizing (Competitive) Neuromuscular Blockers: Pharmacological Actions

    Nondepolarizing neuromuscular blockers prevent the membrane depolarization of muscle cells and inhibit muscle contraction. These are usually administered with anesthetics to achieve complete muscle relaxation. Upon administration, these drugs first block the small, rapidly contracting muscles of the face and hands, followed by the larger muscles of the trunk and the intercostal muscles. The diaphragm is the last muscle to be affected.
    Although all competitive neuromuscular blockers are designed...
    Depolarizing Blockers: Mechanism of Action01:28

    Depolarizing Blockers: Mechanism of Action

    Depolarizing blockers act on skeletal muscle fibers' membranes and induce their depolarization. Most depolarizing blockers have two quaternary N+ atoms that bind the nicotinic acetylcholine receptors and cause neuromuscular blockade within minutes.
    Succinylcholine is the most commonly used depolarizing blocker. Chemically, it constitutes two molecules of acetylcholine joined together by an acetate methyl group. They act on the receptors in the same way as acetylcholine. Because succinylcholine...
    Cardiopulmonary Resuscitation IV: Pharmacological Management01:25

    Cardiopulmonary Resuscitation IV: Pharmacological Management

    Pharmacologic intervention is crucial in treating cardiac arrest patients during ACLS or Advanced Cardiovascular Life Support. The ACLS algorithms guide the administration of specific drugs based on the patient's cardiac arrest rhythm, which includes pulseless ventricular tachycardia (VT), ventricular fibrillation (VF), asystole, and pulseless electrical activity (PEA).EpinephrineIndication: Epinephrine is the first-line drug for all cardiac arrest rhythms.Mechanism of Action: Epinephrine...